Vol.28 Double-foliot Japanese Clock / Otona no Kagaku (Science for Adults) Magazine / otonanokagaku.net


		Modified A4/100 pages/On sale July 28, 2010 ● Supplement: Double-foliot Japanese Clock

Click to watch a video on the Japanese Clock

Try Building a Mechanical Clock of the Edo Period

Edo-period Japan employed a "system of unequal hours" which used the light of the sun.
Based on nightfall and daybreak, the length of a single hour changed from day to day and even varied between night and day, with the Japanese clock being the only mechanical clock in the world that used this unusual system.

The front/rear foliots switch between Brighter 6 o'clock and Darker 6 o'clock automatically.
The two foliots, one for the day hours and one for the night hours, work to advance the hand in two ways.

The clock hand is a single-hand type. It makes one rotation around the clock face each day.
You can also have fun using the Techno DIY set with the Japanese Clock if you link the leaf switch connected to the second wheel up to the Japanino.